As an example of such facilities, mention can be made of: the option of storing phone book type data, facilitating access both to "basic" services and to "value-added" operator services (such as interactive services, in particular), or indeed to perform operations on "supplementary" services (for example call forwarding, barring outgoing calls, etc. . . . ), or indeed, for mobile telecommunications networks that provide not only a telephony service but also a service for transmitting short alphanumeric messages, the option of storing short alphanumeric messages to be transmitted, or as received, by said terminals.
It is known to store data related in this way to such facilities in the terminal itself, or for greater flexibility, in an element referred to as a "subscriber identity module" which, in practice, is in the form of a smart card designed to be inserted in the terminal to enable it to be used, said card also being referred to as an "SIM" card (for "subscriber identity module") in the mobile telecommunications system known under the name GSM (for "Global System for Mobile communications").
As laid down in GSM Recommendation 11.11, the data relating in this way to such facilities, together with the data relating to subscriber identity, is stored in predetermined memory zones of the card, in such a manner as to ensure that the card is compatible with the various types of GSM terminal that might receive it. It is thus possible to take advantage of said facilities from any terminal capable of receiving such a card.